Cartridge-based analytical instrument with optical detector

ABSTRACT

An analytical instrument for analyzing fluids. The instrument includes a cartridge carousel assembly which receives analytical cartridges. The cartridges are self-contained units which incorporate a sample metering/separation system which is operated by centrifugal force. The cartridge carousel is composed of a cartridge rotor plate which includes a center and a plurality of cartridge ports which are located in spaced relation radially outward from the center of the plate. The analytical instrument further includes an optical detector which measures a detectable analytical property of the fluid sample which is provided by the optical element of the cartridge. The optical detector includes a radiation source which shines a beam of radiation on the optical element. The optical detector further includes a return beam detector which measures the return beam of radiation emitted by the optical element. The radiation source and return beam detector are both located on the same side of the cartridge rotor plate. The analytical instrument includes a tracking and control unit which tracks and controls the rotary drive mechanism and the detector to provide coordinated operation so that the optical detector can make measurements of the optical element while the cartridge rotor is stationary or rotating.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to systems and methodswhich are used to analyze fluids which may or may not contain solidcomponents. More particularly, the present invention relates toinstruments and methods which are used in clinical laboratories andother healthcare locations to analyze blood and other bodily fluids.

[0003] 2. Description of Related Art

[0004] Clinical chemistry involves the qualitative and quantitativeanalyses of body fluids, such as blood, urine, spinal fluid and othermaterials. Clinical chemistry encompasses multiple specialty testingareas including coagulation, hematology, immunochemistry, as well aschemistry. The test results derived from such analyses are used byphysicians and other healthcare professionals to diagnose, monitor andtreat diseases. The analysis protocols, instrumentation and otherequipment utilized in clinical laboratory testing must be capable ofproviding accurate and repeatable test results. In addition, it isdesirable that the procedures and instrumentation be simple andefficient. The testing equipment and procedures should be versatileenough that they can be used in healthcare locations where relativelyfew samples are tested as well as in larger clinical laboratories wherethe number of samples being tested on a daily basis is quite large.

[0005] Another consideration in designing analytical equipment for useby healthcare personnel is the amount of sample available for testing.In many situations, the amount of blood or other bodily fluid availableis relatively small. Accordingly, there has been a trend in clinicalchemistry to develop analytical systems which are capable of conductingnumerous different chemical analyses on relatively small amounts ofsample. In general, the goal has been to develop clinical analyticalsystems which provide the maximum number of medical tests utilizing theminimum amount of sample. In such systems, it is essential that thesample be accurately metered to provide a precise aliquot of sample fortesting.

[0006] In achieving the above goals, a multitude of different analyticalprocedures and approaches have been investigated. In one approach,instruments have been developed which have a single sample introductionsite. The equipment is designed so that the sample is split, metered androuted to various locations within the system where multiple chemicalanalyses take place. Other systems do not include internal samplesplitting/metering devices and rely on the clinical chemist to separatethe sample into small aliquots which are introduced into variousinstruments which are capable of conducting a maximum of only a fewchemical analyses at one time.

[0007] There is a continuing need to develop and provide clinicalchemistry instruments which are not only accurate, but versatile enoughto meet the demands of modern medicine. The instruments should be simpleenough to be used by not only highly-skilled laboratory technicians, butalso by other healthcare personnel who may only be required to conductlaboratory tests intermittently. The instruments and procedures shouldbe compact and versatile enough so that they can be utilized in clinicallaboratories which analyze thousands of samples daily, while at the sametime being adaptable to doctors' offices, home healthcare agencies andnursing homes where the number of tests being conducted is not as great.In addition, the instruments should be versatile enough to be useful inconducting a wide variety of blood analyses which are presently beingroutinely utilized. The instruments should also be adaptable toconducting blood or other bodily fluid tests which will be developed inthe future.

SUMMARY OF THE INVENTION

[0008] In accordance with the present invention, an analyticalinstrument is provided which is compact and versatile. The instrument isa “cartridge-based” instrument in that it is designed to receive andprocess individual self-contained cartridges which are pre-loaded withsample and any required reagents. The instrument also utilizescentrifugal force and pressure to meter and transport sample andreagents within the cartridge during the analysis process. Theinstrument is capable of simultaneously analyzing multiple testcartridges. The multiple test cartridges may be set up to conduct thesame or different analytical tests. The instrument is extremelyversatile because the cartridges are designed to carry out a widevariety of test protocols.

[0009] The instrument includes a cartridge carousel assembly whichreceives the analytical cartridges. The cartridges are self-containedunits which incorporate a sample metering/separation system which isoperated by centrifugal force. The cartridge may also include a sampletransport system which is operated by externally-applied pressurewherein the sample is transferred to a test element which provides adetectable analytical property of the fluid sample. The cartridgesinclude an optical element which is optically accessible from only oneside of the cartridge. The optical element provides an opticallydetectable analytical property of the fluid sample being tested.

[0010] The cartridge carousel is composed of a cartridge rotor platewhich includes a center and a plurality of cartridge ports which arelocated in spaced relation radially outward from the center of theplate. The cartridge ports are shaped to receive and hold the cartridgesduring testing procedures. The cartridge carousel assembly furtherincludes a rotary drive mechanism which rotates the cartridge rotorplate about the center thereof. It is this rotation of the cartridgerotor plate which activates the metering/separation system of thecartridge.

[0011] The analytical instrument further includes an optical detectorwhich measures the detectable analytical property of the fluid samplewhich is provided by the optical element of the cartridge. The opticaldetector includes a radiation source located relative to the cartridgerotor to provide an incident beam of radiation which contacts theoptical element. A return beam of radiation is emitted by the opticalelement in response to contact by the incident beam of radiation. Theoptical detector further includes a return beam detector which measuresthe return beam of radiation. As a feature of the present invention, theradiation source and return beam detector are both located on the sameside of the cartridge when it is located within the cartridge rotorplate.

[0012] As a further feature of the present invention, the analyticalinstrument includes a tracking and control unit which tracks andcontrols the rotary drive mechanism and the detector to providecoordinated operation so that the optical detector can make measurementsof the optical element while the cartridge rotor is stationary orrotating. The tracking and control unit includes a user input interfacefor receiving data input from the operator of the instrument as well asa central processing unit, a real time processor and a data outputinterface which provides output of results of the measurements made bythe detector.

[0013] The analytical instrument in accordance with the presentinvention is well-suited for conducting a wide variety of clinicaltests. The versatility of the instrument is only limited by thedifferent types of test cartridges. The instrument is compact and simpleto use. Accordingly, it can be used in a wide variety of settingsranging from large clinical laboratories which conduct thousands oftests daily to small hospital laboratories or doctors offices.

[0014] The above discussed features and attendant advantages of thepresent invention will become better understood by reference to thefollowing detailed description when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a perspective view of a preferred exemplary analyticalinstrument in accordance with the present invention showing the outerhousing thereof. Also shown in FIG. 1 are analytical cartridges whichare designed to be processed by the instrument.

[0016]FIG. 2 is a perspective view of an analytical instrument inaccordance with the present invention wherein the housing cover and userinterface has been removed.

[0017]FIG. 3 is a top view of the preferred exemplary analyticalinstrument shown in FIG. 2.

[0018]FIG. 4 is a perspective view of the preferred exemplary instrumentin which the top portion has been removed to expose the cartridge rotorplate.

[0019]FIG. 5 is a view of the rotary drive mechanism and real timeprocessing unit which is located at the bottom of the instrument asshown in FIGS. 2-4.

[0020]FIG. 6 is a detailed view of the cartridge rotor plate.

[0021]FIG. 7 is a detailed view of the cartridge rotor plate which showsthe locking mechanism which holds the cartridge in place during rotationof the cartridge plate as well as the balancing mechanism which ensuresthat the rotor plate is balanced to ensure non-asymmetric rotation.

[0022]FIG. 8 is an exploded view of a preferred exemplary analyticalcartridge which includes a test element which is designed to be usedwith a reflectance detector system.

[0023]FIG. 9 is a side view of the reflectance test cartridge shown inFIG. 8.

[0024]FIG. 10 is a bottom view of the reflectance cartridge shown inFIG. 8.

[0025]FIG. 11 is a perspective view of a preferred exemplary testcartridge which includes a pressure-operated reagent transport systemand an electrochemical test element.

[0026]FIG. 12 is a view of the cartridge shown in FIG. 8 showing a barcode reading strip which is used by the instrument to provide trackingand control of cartridge processing.

[0027]FIG. 13 is an exploded view of the electrochemical cartridge shownin FIG. 11.

[0028]FIG. 14 is an exploded view of the electrochemical cartridge ofFIG. 11 showing the electrochemical test element.

[0029]FIG. 15 is a partially exploded view of an analytical cartridge inaccordance with the present invention which includes a cuvette testelement which allows transmittance-based detection by the analyticalinstrument.

[0030]FIG. 16 is a detailed view of the cuvette which forms part of thetransmittance analytical test cartridge shown in FIG. 15.

[0031]FIG. 17 is a sectional view of FIG. 16 which depicts the pathwayof light through the cuvette detector.

[0032]FIG. 18 is a bottom view of the upper housing plate which islocated on top of the cartridge rotor plate. This figure depicts aseptum actuator, vent seal element and actuator mechanism which formpart of the sample transport system which contact the cartridges duringprocessing by the instrument. The figure also depicts the actuatormechanisms which actuate the reagent transport system in the cartridge.

[0033]FIG. 19 is an exploded view of the optical detection unit which islocated at a position within the analytical instrument below thecartridge rotor plate.

[0034]FIG. 20 shows the elements of the electrochemical detection systemwhich are located in the lower housing of the preferred exemplaryinstrument.

[0035]FIG. 21 is a more detailed view of FIG. 20 showing theelectrochemical contact pins and actuator assembly.

[0036]FIG. 22 shows the encoding assembly located in the bottom portionof the instrument which provides tracking and control of the cartridgerotor plate.

[0037]FIG. 23 is a perspective view of the bar code reader which islocated in the top portion of the instrument.

[0038]FIG. 24 is an alternate perspective view of the bar code readershown in FIG. 23 with the light-emitting diodes (LED) on one side beingexposed.

[0039]FIG. 25 is a perspective view of the housing plates which surroundthe cartridge rotor plate. The housing plates include heating elementswhich are operated to maintain controlled temperature during processingof the cartridges.

[0040]FIG. 26 is an exploded view of the preferred exemplary sampletransport actuator system in accordance with the present invention.

[0041]FIG. 27 is a perspective view of the assembled sample transportactuator.

[0042]FIG. 28 shows vent actuator block which forms part of the sampletransport actuator mechanism.

[0043]FIG. 29 shows the preferred exemplary reagent pouch actuator andrelated actuating mechanism.

[0044]FIG. 30 is an exploded view of the reagent pouch actuator assemblyshown in FIG. 29.

[0045]FIG. 31 is a perspective view of the cartridge rotor plate whereinthe platter caps have been removed to show the cartridge latchingmechanism.

[0046]FIG. 32 is a detailed view of the sample cartridge ejectionmechanism.

DETAILED DESCRIPTION OF THE INVENTION

[0047] A preferred exemplary analytical instrument in accordance withthe present invention is shown generally at 10 in FIG. 1. The outerhousing of the instrument is shown in more detail in copending designpatent application Ser. No. ______. The instrument is designed toreceive and process self-contained analytical cartridges such as thoseshown generally at 12. The cartridges 12 include test elements whichutilize reflectance, transmittance or electrochemistry. Thetransmittance type analytical cartridge is shown in FIGS. 8-10 and 12.This type of cartridge is also described in detail in internationalapplication No. PCT/US98/15616. This type of cartridge will also bedescribed briefly below.

[0048] The type of analytical cartridge which utilizes anelectrochemical test element is shown in FIGS. 11, 13 and 14. Suchelectrochemical test cartridges are also described in copending patentapplication Ser. No. 09/079,034, which was filed on May 14, 1998, and ispublished as International patent application No. ______. Theelectrochemical cartridge will also be briefly described below. Thetransmittance type analytical cartridge is shown in FIGS. 15-17. Thistype of cartridge is also described in detail in International patentapplication No. PCT/US99/01707.

[0049] The detailed descriptions of the three types of analyticalcartridges set forth in the above three pending applications are herebyincorporated by reference. The brief description of these cartridges setforth later on in the body of this specification is provided to show howa preferred exemplary embodiment of the present analytical instrumentoperates. It will be understood by those skilled in the art that theanalytical instrument of the present invention may be utilized foranalyzing other analytical cartridges which have similar properties tothe preferred exemplary cartridges described herein and set forth in theabove-referenced patent applications.

[0050] Referring again to FIG. 1, the analyzer 10 includes an upperhousing cover 14 and a lower housing cover 16. A computer input/outputpad or screen 18 is located in the upper cover 14 to allow the operatorof the instrument to view information and input. The housing cover 14further includes an inlet port 20 through which the cartridges 12 areinserted into the instrument. A central processing unit is locatedwithin the upper housing cover 14. A disc inlet 22 is provided forallowing the operator to insert floppy disks into the central processingunit to provide software updates as well as transport other data andinformation into and out of the central processing unit. The upperhousing cover 14 also includes a port and shelf 24 where a paper copy ofreport results and other data is made available to the operator.

[0051] The analyzer is shown in FIGS. 2-4 with the housing covers andcentral processing unit removed. The instrument includes a cartridgecarousel assembly shown generally at 26, a detector assembly locatedbelow the cartridge carousel assembly 26 and shown generally at 28 and atracking and control unit which is located in the bottom of theinstrument and is shown generally at 30. The tracking and control system30 includes two circuit boards 29 and 31 which are connected to thecentral processing unit and a real-time processor to provide overalltracking and control functions for the instrument.

[0052] The cartridge carousel assembly includes a cartridge rotor plate32, a rotary drive mechanism 34 and sample/reagent actuators 36. Aretractable door 35 is provided which can be lowered to allow cartridges12 to be introduced into the rotor plate 32. As shown in FIG. 5, therotary drive mechanism 34 includes a motor and pulley assembly 38 whichdrives belt 40 and pulley 42 which is connected to driveshaft 44. Thecartridge rotor plate 32 is connected to the driveshaft 44. An encodingassembly 46 is provided to track the position of the cartridge rotorplate 32 and provide outputs which are part of the tracking and controlsystem which operate motor 38 to provide controlled stopping androtation of cartridge rotor plate 32 at various times and at variousspeeds.

[0053] The cartridge rotor plate 32, as best shown in FIGS. 6, 7 and 31,includes a center 48 and a plurality of cartridge ports 50 which arelocated in spaced relation radially outward from the center 48. Thecartridge ports 50 are shaped to receive the analytical cartridges whichare shown in FIGS. 8-17. An exemplary cartridge 12 is shown in positionwithin the cartridge rotor plate 32 (see FIG. 6). The rotor plate 32includes locking tabs 52 which are located on either side of port 50.The locking tabs 52 engage the sides of cartridge 12 to lock it in placeduring centrifugation of the cartridges. The rotor plate 32 furtherincludes balance weights 54 which are connected to a support yoke 56.

[0054] The cartridge ports 50 are divided into two sections. An outercartridge dock 58 and an inner balance weight dock 60. When thecartridge 12 is inserted into the cartridge dock 58, as shown in FIG. 6,the balance weight 54 and yoke assembly 56 are pushed via a yokemounting track into the balance weight dock 60. The movement of thebalancing weight 54 and yoke 56 from the cartridge dock 58 into thebalance weight dock 60 is represented by arrow 62 in FIG. 7. The yoke 56is held in place and guided by top plates 57. In FIG. 31, the rotorplate 32 is shown with the top plates 57 being removed.

[0055] As the cartridge 12 is moved into dock 58, it contacts tabs 52and pushes the tabs 52 outward. The tabs 52 are connected to arms 53.The arms 53 include inner tabs 64 which are spring-biased inward bysprings located between the arms at 55 in FIG. 31. The springs are notshown. Once the cartridge 12 reaches its final location in dock 58, thetabs are spring-biased into locking engagement with indentations in thecartridge 12. The inner tabs 64 are located so that they do notinterfere with movement of the weight 54 into the balance weight dock60.

[0056] If a cartridge 12 is not inserted into dock 58, the balanceweight 54 and yoke 56 remain within the cartridge dock 58 duringrotation of plate 32. This provides balancing of the plate 32 tosubstantially reduce vibration and prevent possible damage which mightoccur during high-speed rotation of an unbalanced plate. Thiscounterbalance system allows the operator to insert as few as onecartridge into the instrument for analysis or as many as six. An evenlarger number of cartridges can be inserted into the cartridge rotorplate if the number of ports is increased. Referring to FIG. 6, thebalance weight located in the port 50 which is adjacent to the cartridge12 (counterclockwise) is shown located within the balance weight dock60. Upon initial rotation, this particular counterweight will slideoutward into the cartridge dock 58 to provide balancing of the plate 32.

[0057] As mentioned above, the cartridges 12 which are processed by theanalytical instrument of the present invention can be of at least threetypes. The first type is shown at 66 in FIGS. 8-10 and 12. The cartridge66 includes a body 68, top plate 70, label 72 and cover 74. The concavecurve in the cartridge body sides may be eliminated as shown in phantomat 75 in FIG. 10, if desired. The cartridge includes a samplemetering/separation system which is shown at 76 in FIG. 8. The sample isintroduced into the system 76 through sample introduction portion 78.The system also includes a vent port 80 which is required for properoperation of the system.

[0058] The system 76 is designed to meter out an accurate sample aliquotwhen the cartridge is subjected to centrifugation. In addition, thesystem 76 is designed to provide separation of solid components, such asblood cells, from the sample during centrifugation, if desired. Thecartridge 66 also includes a flexible septum 82 which forms an essentialpart of the cartridge's pressure-operated sample transport system. Aswill be described in more detail below, the analytical instrument of thepresent invention includes a sample transport actuator which compressesseptum 82 in order to pressurize the system 76 and transport thepreviously-metered sample to the test element. The two basic steps ofthe analytical process are centrifugation of the cartridge to achievemetering and separation of the sample followed by pressurization ofsystem via septum 82 to transport the sample to the test element.

[0059] The test element for cartridge 66 is reflectance reagent plate 84which is held in place within the cartridge by retainer 86.Pressurization of septum 82 transports the sample through system 76 intocontact with the reagent plate 84. The result is a detectable analyticalproperty. This analytical property is measured by the analyticalinstrument, as will be described in more detail below, by focusingradiation of a selected wavelength onto plate 84 and measuring theamount of radiation which is reflected back to a detector. Both theradiation source and reflectance detector are located below thecartridge rotor plate 32.

[0060] A second type of analytical cartridge is shown at 88 in FIGS. 11,13 and 14. Cartridge 88 is similar to cartridge 66 in that it requirescentrifugation followed by pressurization in order to carry out analysisof a given sample. The principal differences are that the cartridge 88includes a system for transporting reagent to the test element and,instead of using a reflectance test element, cartridge 88 utilizes anelectrochemical measuring device.

[0061] The electrochemical analytical cartridge 88 includes a body 90,top plate 92, cover 94 and flexible septum 96. The cartridge 88 alsoincludes a flexible reagent pouch 98 which is compressed and puncturedby a reagent transport actuator to transport reagent to theelectrochemical detector which is shown at 100 in FIG. 14. Likecartridge 66, cartridge 88 also includes a label 104. Both labels 104 oncartridge 88 and label 72 on cartridge 66 preferably include a bar codewhich is shown at 106 in FIG. 12. This bar code is read by theinstrument to provide input of data which is specific to the particularcartridge. This information is used by the tracking and control systemof the analytical instrument to coordinate the rotary drive mechanismfor the cartridge rotor plate and the actuators which operate againstthe flexible septums and flexible reagent pouches.

[0062] The electrochemical cartridge 88 also includes a sample inletport 108 and vent port 110. The sample metering and transport system isshown at 112 in FIG. 13. This system typically does not include theplumbing required for separation of solid components from the samplebecause, in general, electrochemical tests do not require separation ofsolids from the sample. However, the system shown at 112 may be modifiedto provide sample separation, if desired.

[0063] The cartridge cover 94 is opened in order to allow the operatorto place a sample into the cartridge through port 108. The cover is thenclosed as shown in FIG. 12 and the cartridge inserted into one of theports 50 in cartridge rotor plate 32. The cartridge is then centrifugedat sufficient speeds and for a sufficient time to meter out an accurateamount of sample within system 112. Septum 82 is then actuated totransport sample liquid to the electrochemical detector 100. Inaddition, flexible reagent pouch 92 is also compressed. Compression offlexible pouch 98 causes the pouch to be punctured and reagent to betransported to the electrochemical detector 100. The instrument includesan electrochemical detector probes, which will be described in furtherdetail below. The probes contact the electrochemical detector 100 tomeasure the results of electrochemical testing.

[0064] A third type of exemplary cartridge which is processed by theanalytical instrument of the present invention is shown in FIGS. 15-17.This type of cartridge is a transmittance-type analytical cartridgewhich is shown at 114 in FIG. 15. The transmittance cartridge 114includes a cartridge body 116, top plate 118, cover 120 and septum 122.The transmittance cartridge 114 further includes a cuvette 124 which isheld in place by retainer 126. The cuvette 124 is a test element whichis capable of being exposed to spectral radiation in order to providespectroiphotometric test results. The cuvette 124 is shown in moredetail in FIGS. 16 and 17.

[0065] The cuvette 124 includes optical wings 128 and 130 which directspectral radiation through the cuvette test zone or cell 132 as shown byphantom line 134 in FIG. 17. As will be described in detail below, theanalytical instrument of the present invention includes a detectorsystem which has a spectral radiation source shown schematically at 136in FIG. 17 which is located below the cartridge rotor plate 32. Thespectral radiation source directs a focused beam of radiation 134 up towing 130 which in turn directs the beam through the cuvette test zone ortest cell 132 to wing 128 and back down to a detector shownschematically in FIG. 17 at 138.

[0066] The internal operation of the three types of cartridges have onlybeen briefly described above in order to provide an understanding of theoperation of the analytical instrument 10. A more detailed descriptionof the three types of cartridges can be found in the above-referencedInternational patent applications.

[0067] A bottom view of the upper portion 140 of the cartridge carouselassembly 26 is shown in FIG. 18. The upper portion 140 is also shown inplace on instrument 10 in FIG. 2. A sample transport actuator is showngenerally at 141 in FIGS. 2, 18 and 26. The actuator 141 includes aseptum actuator rod 142 is provided which is movable into contact withthe flexible septums on the analytical cartridges to move the septumsfrom a relaxed position to one or more compressed positions to providetransport of metered and/or separated samples to the cartridge testelement. A vent seal rod 146 is also provided which is designed tocontact and seal the cartridge vent which is shown at 80 in FIG. 8, 110in FIG. 11 and not shown on the cartridge in FIG. 15.

[0068] As best shown in FIGS. 26-28, the sample transport actuatormechanism 141 includes a motor 143, pusher cover 145, vent block 147,main pusher block 149, vent block spring 151 and vent seal rod spring155. The vent seal rod 146 includes a tip 163. The block 149 is moved upand down by motor 143 via drive shaft 165. As best shown in FIG. 27, thevent seal rod tip 163 extends below the tip of the septum actuator rod142. As a result, the vent seal rod tip 163 contacts and seals thecartridge vent prior to the septum actuator rod 142 compressing theflexible septum. It is necessary that the cartridge vent be closed priorto compression of the flexible septum. Otherwise, adequatepressurization of the cartridge may not be achieved to provide desiredsample transport.

[0069] In addition, the sample transport actuator mechanism 141 mustalso provide for retraction of vent seal rod 146 from its sealingposition against the cartridge prior to retraction of the septumactuator rod 142. By retracting the vent seal rod 146 first, pressurewithin the analytical cartridge is released uniformly. This eliminatesthe possibility of disturbing liquids within the cartridge plumbing dueto premature movement of the flexible septum back to the septum'sinitial relaxed position. A wide variety of different possiblemechanisms are possible to achieve this condition wherein the vent sealrod provides a seal prior to septum compression and releases the sealprior to septum relaxation. However, it is preferred that asolenoid-operated release system be used as shown in FIGS. 26 and 27.This system employs a solenoid 148 which operates a push lever 167 whichis connected to seal rod 146 by lever spring 169. Operation of solenoid148 moves lever 167 which releases the vent seal rod 146 so that itmoves upward in vent block 147. Once the vent seal rod 146 is released,the main pusher block 149 is withdrawn to release the septum rod 142from contact with the cartridge septum. To reset the vent seal, the ventseal rod 146 is moved to the position shown in FIG. 27, where a resetpin 177 is pushed against reset bar 179.

[0070] A reagent transport actuator is shown generally at 183 in FIGS.18, 29 and 30. The reagent actuator 183 includes a reagent pouchactuator rod 150. The reagent actuator rod 150 is controlled by actuatormotor 152. The rod 150 and actuator motor 152 form a reagent actuatormechanism which moves the reagent pouch on the analytical cartridge froma relaxed position to one or more compressed positions. A tip 185 isplaced over the rod 150. The tip 185 is connected to a block 187. Aspring 189 biases the tip 185 away from rod 150. During compression ofthe reagent pouch, the spring 189 becomes slightly compressed as the tip185 is seated against the rod 150.

[0071] During compression of the reagent pouch, a spike or other elementin the cartridge punctures the reagent cartridge to allow release andpressurized transport of the reagent. The spring 189 provides a constantpressure bias against the pouch even as it is punctured and releasesfluid. The reagent actuator rod 150, septum actuator rod 142 and ventseal rod 146 are all shown in their retracted position in FIG. 18. Thevarious rods are moved into contact with the cartridges as controlled bythe tracking and control system of the instrument. The system iscoordinated so that the actuator rods only move into contact with acartridge when the cartridge rotor plate 32 is stationary. If desired,additional reagent pouch actuators and associated actuator mechanismsmay be included in the instrument to handle cartridges which may havetwo or more reagent pouches which require simultaneous actuation.

[0072] Ejection of cartridges 12 from rotor plate 32 is accomplished byan ejection mechanism which is shown at 153 in FIGS. 18 and 32. Themechanism 153 includes an ejection arm 154, guide rod 155 and drivemotor 156. The actuator arm 154 is shown in a retracted position. Theactuator arm 154 moves in the direction of arrow 157. The ejectionactuator arm 154 is operated by motor mechanism 156. The actuator arm154 ejects the cartridge 12 by first moving inner tabs 64 outward.Movement of inner tabs 64 outward also moves arms 53 and attached tabs52 outward to release cartridge 12. The actuator arm 154 continues tomove outward to move the counter weight 54 to the position shown in FIG.7 and eject cartridge 12. The tracking and control unit of theinstrument controls the ejection mechanism 153 and rotary drivemechanism 34 so that the cartridges are only ejected when they arelocated at ejection port 159 (see FIGS. 2 and 4).

[0073] A magnetic mechanism 161 is located adjacent to the ejector 153.The magnet 161 is used in combination with magnetic particles which maybe included in the cartridges to provide mixing of reagents and sampleswithin the cartridges as they pass by the magnet.

[0074] A preferred exemplary optical detector is shown at 158 in FIG.19. The optical detector 158 is located directly below the cartridgecarousel assembly 26. The optical detector 158 includes seven LED's 160.The optical detector 158 further includes collimator elements 164 and166 which direct spectral radiation from the LED upward through thedetector as represented by phantom line 168. The radiation path for onlythe central LED is shown. The collimating elements 164 and 166 directthe other LED beams in the same manner. The detector 158 furtherincludes a beam control plate 170 which includes six slits 172 and onesmaller slit 162. The slits 172 and 162 further reduce the size of LEDbeams 168 so that the final radiation beams 168 which contacts the testelement of the analytical cartridge has a small cross-sectional area.The test element of the analytical cartridge is shown diagrammaticallyat 174 in FIG. 19. The slit 162 is smaller than the other slits and isdesigned for use with cartridges that include a cuvette.

[0075] The test element, as described above, may include either areflectance test element or a transmittance test element (i.e., thecuvette 124 shown in FIGS. 16 and 17). The optical detector 158 furtherincludes a return beam detector plate 176 which includes four opticaldetector elements 178. The return beam from analytical cartridge 174travels through openings 181 in beam control plate 170. The path of thereturning beam of transmitted or reflected spectral radiation is shownin phantom at 180. Again, for simplicity, the return beam path 180 isshown for only one of the LED's 160.

[0076] A wide variety of radiation sources may be utilized. In thepreferred exemplary embodiment, the light-emitting diodes 160 each havea different wavelength. For example, moving from right to left in FIG.19, the light-emitting diodes will have wavelengths of 425 nanometers,505 nanometers, 570 nanometers, 590 nanometers, 615 nanometers, and 655nanometers. The LED 160 on the far left is used for cuvette cartridgesand preferably emits a wavelength of 570 nm. This range of LEDwavelengths is preferred since it provides measurement beams rangingfrom near-ultraviolet through the visible spectrum to near-infraredwavelengths. A wide variety of LED combinations is possible dependingupon the types of tests being conducted. The tracking and control unitis programmed, depending upon the particular test cartridge beinganalyzed, to expose the cartridge to one or more of the LED wavelengths.In this way, a wide variety of spectrophotometric measurements can bemade.

[0077] As shown in FIG. 19, the optical detector 158 is arcuate inshape. The arcuate shape of the optical detector 158 is matched to thearcuate path of the cartridges as they move during rotation of thecartridge rotor plate 32. In this way, measurements may be taken whenthe cartridge is stationary or when the cartridge is moved past thedetector during rotation of the rotor plate 32. The instrument may beprogrammed so that multiple measurements of the test element 174 may bemade as it moves past the optical detector slits 172. In this way,measurements from one end of the test element to the other can be takenas the test element moves past a particular slit 172. Alternatively, thecartridge test element 174 may be held stationary over the opticaldetector 158 and time-dependent changes in spectral transmittance orreflectance may be measured. It is preferred that the cross-sectionalarea of slits 172 be substantially less than the cross-sectional area ofthe optically-accessible portion of the test element 174 present in theanalytical cartridge. For example, the cross-sectional area of slit 172should be at least one-tenth of the cross-sectional area of theoptically-accessible portion of test element 174. Test beams havingcross-sectional areas which are on the order of one-hundredth of thecross-sectional area of the optically-accessible portion of the testelement are also possible.

[0078] A preferred exemplary electrochemical detector is shown at 182 inFIGS. 20 and 21. The electrochemical detector 182 is located directlybelow the cartridge carousel assembly 26 as shown in FIGS. 2 and 4. Theelectrochemical detector 182 includes electrical contact probes 184which are designed to be moved by actuator mechanism 186 into contactwith the electrochemical detector 100 located on the bottom ofelectrochemical cartridge 88 (FIG. 14). The instrument tracking andcontrol system is set up so that the electrical probes 184 are onlymoved into position by actuator 182 when an electrochemical cartridge isbeing tested. Further, the instrument is programmed so that theelectrical probes 184 are only moved into position when the cartridge islocated over the electrochemical detector 182 and is stationary.

[0079] As part of the tracking and control system, the analyticalinstrument will preferably include a spindle positioning encoder whichis shown at 188 in FIG. 22, and more generally at 46 in FIG. 5. Theencoder is connected to the circuit boards of the tracking and controlunit 30 which are in turn connected with the central processing unit.The encoder 188 is connected to spindle 44 which in turn is connected tothe rotor plate 32. A transparent optical disk 190 is provided which hasindexing marks 192 which include a home index mark 194. A light source196 with corresponding optical detector 198 are provided to detectpassage of the index marks past the optical detector. The combined lightsource and optical detector 196 and 198 provides continual input to thereal-time processing unit and central processor which allows accuratecontrol of rotation speeds and radial location of cartridges, when theyare located within the cartridge rotor plate. Other encoder systems arepossible provided that they are capable of providing the same trackinginformation which is input into the tracking and control system in orderto accurately control rotation and positioning the cartridge rotor plate32.

[0080] The analytical instrument includes a bar code reader which isshown at 200 in FIGS. 2-3 and 23-24. The bar code reader 200 scansarcuate bar codes 201 on the analytical cartridges to provide input intothe tracking and control system regarding the type of cartridge andtests to be run (see FIG. 6). The bar code reader 200 also reads aZ-shaped position calibration label 202 on the rotor plate 32 (FIG. 6).The bar code reader 200 preferably utilizes a 1:1 ratio double-lenscamera and a light source such as LED's 204. The bar code reader alsoincludes a photodiode light detector 206. As the alternating light anddark segments of the bar code 201 pass before the bar code reader 200,they are illuminated by the light source 204 and projected onto thephotodiode detector chip 206 as a series of light pulses. The detectorchip 206 is preferably a linear array of 128 photodiode elementsoriented such that light reflected from each bar code element shinesupon about three or more photodiode elements. The bar code reader 200 isalso adapted to scan the Z-shaped position calibration label 202 on thespinning rotor plate 32. The bar code reader 200 in conjunction with theencoder 188 provide input into the central processing unit and/orreal-time processor which allows the position of the rotor plate to beaccurately determined and controlled.

[0081] It is preferred that the cartridge rotor plate be maintained atconstant temperature. For many cartridges, test results will vary if thetemperature is not kept constant. In addition, some tests must beconducted at elevated temperatures. Accordingly, it is preferred thattwo heating plates 210 and 212 be located on either side of thecartridge rotor plate 32 as shown in FIG. 25. The heater plates orplatens are preferably electrically heated. However, other types oftemperature control systems may be used. The spinning of the rotor plateat relatively high speeds (e.g. 1500 rpm) facilitates heating because ofthe uniform and constant mixing of air and heat generated by the rotor.

[0082] Having thus described exemplary embodiments of the presentinvention, it should be noted by those skilled in the art that thewithin disclosures are exemplary only and that various otheralternatives, adaptations, and modifications may be made within thescope of the present invention. Accordingly, the present invention isnot limited to the specific embodiments as illustrated herein, but isonly limited by the following claims.

What is claimed is:
 1. An analytical instrument for analyzing fluids,said instrument comprising: A) a cartridge carousel assembly whichreceives analytical cartridges, wherein each of said cartridgescomprises a top side, bottom side, an analytical system which requirescentrifugal force to operate and a test element which comprises anoptical element which is optically accessible from only one side of saidcartridge and wherein said optical element provides an opticallydetectable analytical property of said fluid, said cartridge carouselassembly comprising: a) a cartridge rotor plate which comprises a centerand a plurality of cartridge ports which are located in spaced relationradially outward from said center; and b) a rotary drive mechanism whichrotates said cartridge rotor plate about the center thereof, whereinrotation of said cartridge rotor plate provides the centrifugal forcerequired to operate the analytical system of said cartridge; B) anoptical detector which measures said detectable analytical property ofsaid fluid sample which is provided by the optical element of saidcartridge, said optical detector comprising: a) a radiation sourcelocated relative to said cartridge rotor to provide an incident beam ofradiation which contacts said optical element and wherein a return beamof radiation is emitted by said optical element in response to contactby said incident beam of radiation; and b) a return beam detector whichmeasures said return beam of radiation wherein said radiation source andreturn beam detector are both located on the same side of said cartridgewhen it is located within said cartridge rotor plate; and C) a trackingand control unit which tracks and controls said rotary drive mechanismand said detector to provide coordinated operation so that said opticaldetector can make measurements of said optical element while saidcartridge rotor is stationary or rotating, said tracking and controlunit comprising a user input interface for receiving data input from auser of the instrument, a central processing unit, a real time processorand a data output interface which provides output of results of themeasurements made by said optical detector.
 2. An analytical instrumentaccording to claim 1 wherein said radiation source comprises: aplurality of light emitting diodes which are arranged to form an arcuatearray of light emitting diodes which corresponds to the arcuate path ofsaid optical element as said cartridge travels in said cartridge rotorplate during rotation of said cartridge rotor plate.
 3. An analyticalinstrument according to claim 2 wherein said radiation source comprisesone or more light emitting diodes which emit radiation in a wavelengthselected from the group consisting of ultra-violet, visible andinfra-red.
 4. An analytical instrument according to claim 3 wherein saidradiation source comprises: a first light emitting diode which emitsradiation consisting of a wavelength of about 425 nanometers; a secondlight emitting diode which emits radiation consisting of a wavelength ofabout 505 nanometers; a third light emitting diode which emits radiationconsisting of a wavelength of about 570 nanometers; a fourth lightemitting diode which emits radiation consisting of a wavelength of about590 nanometers; a fifth light emitting diode which emits radiationconsisting of a wavelength of about 615 nanometers; and a sixth lightemitting diode which emits radiation consisting of a wavelength of about655 nanometers.
 5. An analytical instrument according to claim 4 whichcomprises a seventh light emitting diode which emits radiationconsisting of a wavelength of about 570 nanometers.
 6. An analyticalinstrument according to claim 2 wherein the optically accessible portionof said optical element has a cross-sectional area and wherein saidradiation source comprises a collimator which directs said incident beamof radiation onto said optical element as collimated incident beam whichhas a cross-section which is substantially less than the cross-sectionof said optically accessible portion.
 7. An analytical instrumentaccording to claim 5 wherein said tracking and control unit is set totake multiple measurements of the optical element by exposing saidoptical element to a plurality of collimated incident beams andmeasuring the resultant plurality of return beams.
 8. An analyticalinstrument according to claim 6 wherein said radiation source comprisesmultiple collimators wherein the cross-sections of said collimatedincident beams are not the same.
 9. An analytical instrument foranalyzing fluids according to claim 1 which is adapted for use withanalytical cartridges which comprise a top side, bottom side, ananalytical system which requires centrifugal force to operate and a testelement which comprises an electrochemical element which is electricallyaccessible from only one side of said cartridge and wherein saidelectrochemical element provides an electrically detectable analyticalproperty of said fluid, said analytical instrument comprising: anelectrical detector which measures said electrically detectableanalytical property of said fluid sample which is provided by theelectrochemical element of said cartridge, said electrochemical detectorcomprising: a) an electrical probe comprising a surface which is movablebetween a retracted position and an extended position where saidelectrical probe is in contact with said electrochemical element toprovide measurement of said electrically detectable analytical property;and b) a probe actuator assemble which moves said electrical probebetween said retracted position and said extended position; and whereinsaid tracking and control unit tracks and controls said rotary drivemechanism and said electrical detector to provide coordinated operationso that said electrical detector can make measurements of saidelectrochemical element while said cartridge rotor is stationary.